Mitosehemmer
A mitotic inhibitor is a type of drug used mainly to treat cancer. The drug is derived from natural substances, sometimes plant alkaloids.[1] Mitotic inhibitors are also used in certain types of cancer research, including cytogenetics. They work by interfering with and halting mitosis (usually during the M phase of the cell cycle), so that the cell will no longer divide.[2]
Tubulin, a necessary protein for mitosis to occur, is suppressed by the mitotic inhibitor. This prevents mitosis altogether.[3]
Frequently used mitotic inhibitors include paclitaxel, docetaxel, vinblastine, vincristine, and vinorelbine.[4]
Process of general mitotic inhibition
Cancer cells are able to grow and eventually metastisize through continuous mitotic division. Mitotic inhibitors are able to prevent cells from undergoing mitosis, thus preventing cancerous growth. They are able to accomplish this by supressing a protein necesary for cells to undergo mitosis.
Use of mitotic inhibitors in cytogenetics
Cytogenetics, the study of chromosomal material by analysis of G-Banded chromosomes, uses mitotic inhibitors extensively. In order to prepare a slide for cytogenetic study, a mitotic inhibitor is added to the cells being studied. This stops the cells during mitosis, while the chromosomes are still visible. Once the cells are centrifuged and placed in a hypotonic solution, they swell, spreading the chromosomes. After preparation, the chromosomes of the cells can be viewed under a microscope, their banding patterns examined. This experiment is crucial to many forms of cancer research.
Specific Drugs
Taxanes
Taxanes are complex terpenes produced by the plants of the genus Taxus(yews). Originally derived from the Pacific yew tree, they are now synthesized artificially. Their principle mechanism is the inhibition of the cell's microtubule function. Microtubules are essential to mitotic reproduction, so through the inactivation of the microtubule function of a cell, taxanes inhibit the cell's division.
- Paclitaxel - used to treat lung, ovarian, breast cancer, and advanced forms of Kaposi's sarcoma.[5]
- Docetaxel - used to treat breast, ovarian, and non-small cell lung cancer.[6][7]
Vinca alkaloids
Vinca alkaloids are amines produced by the hallucinogenic plant Catharanthus roseus(Madagascar Periwinkle). Like taxanes, vinca alkaloids are also anti-microtubule, inhibiting mitosis in this fashion.
- Vinblastine - used to treat leukaemia, Hodgkin's lymphoma, non-small cell lung cancer, breast cancer and testicular cancer. It is also a component in a large number of chemotherapy regimens.[8]
- Vincristine - used to treat lymphoma, breast cancer, lung cancer, and acute lymphoblastic leukemia.[9]
- Vindesine - used to treat leukaemia, lymphoma, melanoma, breast cancer, and lung cancer.[10]
- Vinorelbine - used to treat breast cancer and non-small-cell lung cancer.[11]
References
See Also
- ↑ http://www.cancer.org/docroot/ETO/content/ETO_1_4X_What_Are_The_Different_Types_Of_Chemotherapy_Drugs.asp
- ↑ http://www.cancer.gov/Templates/db_alpha.aspx?CdrID=46705
- ↑ http://www.drugdigest.org/DD/HC/HCDrugClass/0,4055,47-8,00.html
- ↑ http://www.cancer.org/docroot/ETO/content/ETO_1_4X_What_Are_The_Different_Types_Of_Chemotherapy_Drugs.asp
- ↑ Saville M, Lietzau J, Pluda J, Feuerstein I, Odom J, Wilson W, Humphrey R, Feigal E, Steinberg S, Broder S: Treatment of HIV-associated Kaposi's sarcoma with paclitaxel. In: Lancet. 346. Jahrgang, Nr. 8966, S. 26-8, PMID 7603142.
- ↑ Lyseng-Williamson KA, Fenton C. Docetaxel: a review of its use in metastatic breast cancer. Drugs 2005;65(17):2513-31.
- ↑ Clarke SJ, Rivory LP. Clinical pharmacokinetics of docetaxel. Clin Pharmacokinet 1999;36(2):99-114
- ↑ http://www.cancerbackup.org.uk/Treatments/Chemotherapy/Individualdrugs/Vinblastine
- ↑ http://www.cancerbackup.org.uk/Treatments/Chemotherapy/Individualdrugs/Vincristine
- ↑ http://www.cancerbackup.org.uk/Treatments/Chemotherapy/Individualdrugs/Vindesine
- ↑ http://www.cancerbackup.org.uk/Treatments/Chemotherapy/Individualdrugs/Vinorelbine